Standard RS-170 video is normally presented to a display in the form of 525 lines of data, with a 30 Hz frame rate, using a 2:1 interlace system. Of the 525 lines, 484 may be used to carry the image formation, the remainder being used to provide synchronization information and to allow time for the vertical retrace. A cathode ray tube (CRT) typically recreates an image by scanning the display surface (phosphor screen) twice per frame of incoming video. In the first scan (odd fields), the data for one set of lines is presented to the viewer. In the second scan (even fields), data which is offset to lie between the lines of the previous scan is presented. Thus, one set of the total lines is dark for each field where no second field data is presented to the viewer during the first field, and vice versa.
A flat panel display, whether it is an LCD, an EL or a plasma panel display, is typically operated in a non-interlaced mode. Thus, each pixel dot on the display surface is updated each scan. Prior art has used 1) a field store memory to convert the data format, 2) has scanned the data twice onto the same pixels (even and odd fields are superposed onto each other), or 3) has designed the panel to use a number of rows equal to the scanning standard active row count and scan alternate rows of data.
It is desirable to permit a LCD flat panel to be updated in a non-interlaced mode without requiring the use of an expensive field store memory to perform the conversion from interlaced video input to non-interlaced output. It is also desirable to allow the panel to have any number of rows, either greater than or less than the number of scanning lines, and not require the use of superposition to scan the image.